The present invention relates to an apparatus for controlling a vehicular automatic transmission to shift gears automatically dependent on the power output of the engine on a motor vehicle and the speed of travel of the motor vehicle.
Automatic transmissions are arranged to shift gears (speed ranges) automatically dependent on running conditions of a motor vehicle (such for example as the load on the engine on the motor vehicle, the speed of travel of the motor vehicle, and other parameters) to achieve desired vehicle running characteristics. It is customary to provide a shift map composed of upshifting and downshifting lines for each speed range, the lines being established in relation to the vehicle speed, the opening of a throttle valve, the intake vacuum, etc. which represent the engine power output, and to control the automatic transmission to shift the speed ranges according to the shift map dependent on the changes of traveling states as indicated on the shift map. One example of such shifting control is disclosed in Japanese Laid-Open Patent Publication No. 61-189354, for example.
A shift map is established in order to meet various road conditions such as those of a normal road, an expressway, a mountainous road, and other roads, and hence many factors or considerations are involved in making such a shift map. There are also different demands for shift patterns dependent on whether the driver of an automobile wants to drive the automobile comfortably or in a sporty manner.
It has heretofore been proposed to change a shift map with a selector switch for selecting a normal shift pattern (normal mode) or a sporty shift pattern (power mode) according to the will of the driver, or to switch to a power mode dependent on the degree of the steering operation, the rate at which an accelerator pedal depressed, and the change in the speed ratio of a torque converter (see for example Japanese Patent Publications Nos. 47-36284 and 48-209 and Japanese Laid-Open Patent Publication No. 61-189354).
Each of the selectable shift patterns as described above is however a comprise between various driving needs. Even if normal and power modes, for example, are selectively available, each of these modes is usually established so as to suit the average driver's demand for a shift pattern for such a mode. It has been quite difficult to obtain a shift pattern which would meet the driving needs of all automobile drivers.